Whats the longest stretch of phono cable (unbalanced) i can have between a phono stage and my amp without it causing problems? Having a bit of a move about and could do with knowing.
In general terms, from a low impedance output to a high impedance input (amp) with a ratio of 10 times or more step-up, you should be absolutely fine to run long lengths no problems. As Col has intimated, calcs can be done which determine overall capacitance effects on HF response but knowing your phonostage and your amp loading I would say you can be dead safe with 15 to 20 metres is needed! (based on coax with 65 to 70pF/m capacitance which is typical of most good 75Ohm cables)
You will also need to know the type of cart as well, to calculate the numbers! The RIAA spec says that the max capacitance is 330pF at the MM input. I think that the voltage drop will be relatively small on 10 metres of low capacitance cable, but dont forget to get some very well screened cable, I have used CT100, yes I know it is satellite aerial cable, but it has very low C and a very low insertion resistance as well. Much better to use a balanced type of cable especially if you plan on using a MC cart. Twould be best if you put your coil/MM stage as close to the turntable, and then run the long interconnects to your pre/integrated! S
ITs an electrocomapniet Phonostage into a TAC 300B amp (integrated). Looks like its not gonna be an issue anyway as the stone walls are a bit "odd" to put a shelf onto so length should only be 3/4 metres at max...hopefully. Stu
Capacitance is much much less of an issue with MC carts Stu and the MM capacitative loading is only ever an issue between MM cart and phono stage. From the output of the phonostage to the amp, its effectively line level and post-RIAA so whilst what Stewart has pointed out is perfectly correct between cart and phono stage, its of little relevance between phonostage and amp. Ordinary coax is fine as long as it's a well screened cable (braided). No need to run to balanced cable (which increases total capacitance).
FWIW I've run that sort of distance between passive pre and power amps in the past, without any problems. And that's the sort of thing we're told not to do.
Weeeeeeeelllllllll. Having a granite house the shelf is proving problematic to put up.....We just can't get it up (as the actress said to the bishop). We have hopefully sorted a workaround which means that I can have the amp nearer to the phonostage and hopefully, as I say, a length of interconnects about 3M, perhaps less. It's a RRPITA this Hifi malarkey at times isn't it?
Comments
I've run 10m of cheap as chips interconnect between a DVD player and a preamp once and that worked fine.
The RIAA spec says that the max capacitance is 330pF at the MM input. I think that the voltage drop will be relatively small on 10 metres of low capacitance cable, but dont forget to get some very well screened cable, I have used CT100, yes I know it is satellite aerial cable, but it has very low C and a very low insertion resistance as well. Much better to use a balanced type of cable especially if you plan on using a MC cart.
Twould be best if you put your coil/MM stage as close to the turntable, and then run the long interconnects to your pre/integrated!
S
Looks like its not gonna be an issue anyway as the stone walls are a bit "odd" to put a shelf onto so length should only be 3/4 metres at max...hopefully.
Stu
It's a RRPITA this Hifi malarkey at times isn't it?